Battery cell venting system for electrified vehicle batteries

ABSTRACT

A battery cell according to an exemplary aspect of the present disclosure includes, among other things, a can assembly, an electrode assembly housed inside the can assembly and a venting system including a vent port and at least one of a vent tube inside the can assembly or a spacer plate mounted between the vent port and the electrode assembly.

TECHNICAL FIELD

This disclosure relates to the venting of battery cells of anelectrified vehicle battery pack.

BACKGROUND

The need to reduce automotive fuel consumption and emissions is wellknown. Therefore, vehicles are being developed that reduce or completelyeliminate reliance on internal combustion engines. Electrified vehiclesare one type of vehicle currently being developed for this purpose. Ingeneral, electrified vehicles differ from conventional motor vehiclesbecause they are selectively driven by one or more battery poweredelectric machines. Conventional motor vehicles, by contrast, relyexclusively on the internal combustion engine to drive the vehicle.

A high voltage battery pack typically powers the electric machines andother electrical loads of the electrified vehicle. The battery packincludes a plurality of battery cells that store electric energy. Fromtime to time, gaseous byproducts may be released by the battery cells,such as caused by encounters with off-normal conditions or environments.The battery cells may therefore include vents that allow the gaseousbyproducts to escape from the interiors of the battery cells.

SUMMARY

A battery cell according to an exemplary aspect of the presentdisclosure includes, among other things, a can assembly, an electrodeassembly housed inside the can assembly and a venting system including avent port and at least one of a vent tube inside the can assembly or aspacer plate mounted between the vent port and the electrode assembly.

In a further non-limiting embodiment of the foregoing battery cell, thecan assembly includes a casing and a top plate.

In a further non-limiting embodiment of either of the foregoing batterycells, the vent tube is attached to an interior wall of the casing.

In a further non-limiting embodiment of any of the foregoing batterycells, the vent tube is secured within a corner of the casing.

In a further non-limiting embodiment of any of the foregoing batterycells, the vent tube includes a first height that is less than a secondheight of a wall of the casing.

In a further non-limiting embodiment of any of the foregoing batterycells, the vent port is disposed in the top plate.

In a further non-limiting embodiment of any of the foregoing batterycells, the vent tube establishes a flow pathway between differentportions of the can assembly.

In a further non-limiting embodiment of any of the foregoing batterycells, a plurality of vent tubes are mounted inside the can assembly andeach establishing a flow pathway configured to communicate gaseousbyproducts toward the vent port.

In a further non-limiting embodiment of any of the foregoing batterycells, the spacer plate is mounted to an underside of a top plate of thecan assembly.

In a further non-limiting embodiment of any of the foregoing batterycells, the spacer plate is an arched sheet of material.

In a further non-limiting embodiment of any of the foregoing batterycells, at least one of the vent tube and the spacer plate includes aplurality of perforations.

In a further non-limiting embodiment of any of the foregoing batterycells, the venting system includes both of the vent tube and the spacerplate.

A battery pack according to another exemplary aspect of the presentdisclosure includes, among other things, a battery assembly thatincludes a plurality of battery cells. Each battery cell of theplurality of battery cells includes a venting system comprising a venttube configured to establish a first flow pathway for communicatinggaseous byproducts inside the battery cell and a spacer plate configuredto establish a second flow pathway for communicating the gaseousbyproducts.

In a further non-limiting embodiment of the foregoing battery pack, theventing system includes a vent port.

In a further non-limiting embodiment of either of the foregoing batterypacks, the spacer plate is disposed between the vent port and anelectrode assembly of the battery cell.

In a further non-limiting embodiment of any of the foregoing batterypacks, each of the plurality of battery cells includes a can assemblyincluding a casing and a top plate.

In a further non-limiting embodiment of any of the foregoing batterypacks, the vent tube is disposed in a corner of the casing.

In a further non-limiting embodiment of any of the foregoing batterypacks, the first flow pathway is a vertical flow pathway and the secondflow pathway is a lateral flow pathway.

In a further non-limiting embodiment of any of the foregoing batterypacks, at least one of the vent tube and the spacer plate includes aplurality of perforations.

In a further non-limiting embodiment of any of the foregoing batterypacks, the vent tube is a hollow cylinder and the spacer plate is anarched sheet of material.

The embodiments, examples and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a powertrain of an electrified vehicle.

FIG. 2 illustrates a battery cell for use within a battery pack of anelectrified vehicle.

FIG. 3 illustrates the internal components of the battery cell of FIG.2.

FIGS. 4A, 4B, 4C, 4D and 4E illustrate battery cell venting systems thatinclude vent tubes.

FIG. 4F illustrates an exemplary vent tube of a battery cell ventingsystem.

FIG. 5 illustrates a battery cell venting system according to anotherembodiment of this disclosure.

FIG. 6 illustrates a battery cell venting system according to yetanother embodiment of this disclosure.

FIG. 7 illustrates a battery cell venting system according to yetanother embodiment of this disclosure.

DETAILED DESCRIPTION

This disclosure describes a venting system for venting gaseousbyproducts that may accumulate inside battery cells of an electrifiedvehicle battery pack. An exemplary battery cell includes a can assembly,an electrode assembly housed inside the can assembly, and a ventingsystem for venting the gaseous byproducts. The venting system mayinclude a vent port and either a vent tube inside the can assembly or aspacer plate mounted between the vent port and the electrode assembly.In some embodiments, the venting system includes both the vent tube andthe spacer plate. The proposed venting systems of this disclosureprovide multiple flow pathways within the battery cell for facilitatingventing of the gaseous byproducts. These and other features arediscussed in greater detail in the following paragraphs of this detaileddescription.

FIG. 1 schematically illustrates a powertrain 10 of an electrifiedvehicle 12. Although depicted as a battery electric vehicle (BEV), itshould be understood that the concepts described herein are not limitedto BEV's and could extend to other electrified vehicles, including butnot limited to, plug-in hybrid electric vehicles (PHEV's) or full hybridelectric vehicles (FHEV). Therefore, although not shown in thisembodiment, the electrified vehicle 12 could be equipped with aninternal combustion engine that can be employed either alone or incombination with other energy sources to propel the electrified vehicle12.

In one non-limiting embodiment, the electrified vehicle 12 is a fullelectric vehicle propelled solely through electric power supplied by anelectric machine 14 without assistance from an internal combustionengine. The electric machine 14 may operate as an electric motor, anelectric generator, or both. The electric machine 14 receives electricalpower and provides a rotational output power. The electric machine 14may be connected to a gearbox 16 for adjusting the output torque andspeed of the electric machine 14 by a predetermined gear ratio. Thegearbox 16 is connected to a set of drive wheels 18 by an output shaft20. A high voltage bus 22 electrically connects the electric machine 14to a battery pack 24 through an inverter 26. The electric machine 14,the gearbox 16, and the inverter 26 may collectively be referred to as atransmission 28.

The battery pack 24 is an exemplary electrified vehicle battery. Thebattery pack 24 may be a high voltage traction battery pack thatincludes a plurality of battery assemblies 25 (i.e., battery arrays orgroupings of battery cells) capable of outputting electrical power tooperate the electric machine 14 and/or other electrical loads of theelectrified vehicle 12. Other types of energy storage devices and/oroutput devices can also be used to power the electrified vehicle 12.

The electrified vehicle 12 may also include a charging system 30 forcharging the energy storage devices (e.g., battery cells) of the batterypack 24. The charging system 30 may be connected to an external powersource (not shown) for receiving and distributing power. The chargingsystem 30 may also be equipped with power electronics for converting ACpower received from the external power supply to DC power for chargingthe energy storage devices of the battery pack 24. The charging system30 may also accommodate one or more conventional voltage sources fromthe external power supply (e.g., 110 volt, 220 volt, etc.).

The powertrain 10 of FIG. 1 is shown schematically and is not intendedto limit this disclosure. Various additional components couldalternatively or additionally be employed by the powertrain 10 withinthe scope of this disclosure.

FIGS. 2 and 3 illustrate an exemplary battery cell 56 that may beemployed within an electrified vehicle battery pack, such as the batterypack 24 of the electrified vehicle 12 of FIG. 1, for example. Thebattery cell 56 stores electrical energy for powering various electricalloads of the electrified vehicle 12. The battery pack 24 could employany number of battery cells 56. For example, a plurality of the batterycells 56 may be stacked side by side along a longitudinal axis toconstruct a grouping of battery cells 56, sometimes referred to as a“cell stack” or “module.” The battery pack 24 could also includemultiple individual groupings of the battery cells 56.

In one non-limiting embodiment, the battery cell 56 is a prismatic,lithium-ion cell. However, battery cells having other geometries(cylindrical, pouch, etc.), other chemistries (nickel-metal hydride,etc.), or both, could also benefit from the teachings of the disclosure.

The exemplary battery cell 56 includes a can assembly 58 and anelectrode assembly 60 housed inside the can assembly 58. In onenon-limiting embodiment, the can assembly 58 includes a casing 62 and atop plate 64. The casing 62 includes a plurality of walls 66 that definean interior 68 for housing the electrode assembly 60. The top plate 64of the can assembly 58 may be mounted to the casing 62. In onenon-limiting embodiment, the top plate 64 is welded to the casing 62.The top plate 64 includes terminals 70 (e.g., one positive terminal andone negative terminal). Current collector bars 72 (see FIG. 3) areconnected between the terminals 70 and current-collecting foil surfacesof the electrode assembly 60 within the interior 68 of the casing 62(see FIG. 3). The addition of an electrolyte (e.g., liquid, gel orsolid) allows ionic current flow between the active materials of eachelectrode.

The electrode assembly 60, sometimes referred to as a jelly roll, isformed by winding a positive electrode (e.g., a cathode) with an activecoating, a negative electrode (e.g., an anode) with an active coating,and a separator inserted between the positive electrode and the negativeelectrode. The electrode assembly 60 may be wound about either avertical or horizontal axis. Electrical current flows to and from theactive materials of the positive and negative electrodes. The circuit iscompleted by ionic flow between the electrodes, as supported by theelectrolyte.

The battery cell 56 may additionally include a venting system 74 fordischarging gaseous byproducts from the interior 68. The gaseousbyproducts may be released during a thermal runaway event in which abattery cell 56 heats up faster than the heat can be dissipated, forexample. In one non-limiting embodiment, the venting system 74 includesa vent port 76 for discharging the gaseous byproducts. The vent port 76may be covered with a membrane 78. During certain conditions, gaseousbyproducts released from the electrode assembly 60 may be expelled fromthe interior 68 by communicating these byproducts through the vent port76.

The exemplary venting system 74 may include various additional featuresfor expelling the gaseous byproducts. The various venting systemfeatures discussed below establish multiple flow pathways for expellingthe gaseous byproducts from the battery cell 56 and prevent the ventport 76 from becoming blocked. Incorporation of any or all of theexemplary venting features of this disclosure can mitigate pressurebuild-up inside the battery cell 56 during the rare occurrence of athermal runaway event.

FIGS. 4A-4E illustrate additional features of the venting system 74 ofthe battery cell 56. In one non-limiting embodiment, the venting system74 includes one or more vent tubes 80 that establish flow pathways 85for directing gaseous byproducts GB (see FIG. 4A) along an unobstructedpath toward the vent port 76. The vent tubes 80 may be secured withinthe interior 68 of the casing 62 of the battery cell 56. For example,the vent tubes 80 could be welded or brazed to the walls 66 on theinterior 68 of the casing 62. In one non-limiting embodiment, the venttubes 80 are made of a metallic material. Suitable metallic materialsinclude, but are not limited to, steel and aluminum.

In another non-limiting embodiment, a height H1 of the vent tubes 80 issmaller than a height H2 of each wall 66 of the casing 62 (best shown inFIG. 4A). In this way, gaseous byproducts GB that accumulate in thebottom portion of the casing 62 may be freely vertically communicatedthrough the vent tubes 80 toward the top plate 64, which is typicallywhere the vent port 76 is located. In one non-limiting embodiment, theheight H1 is ⅓ of the height H2. In another non-limiting embodiment, theheight H1 is ½ of the height H2.

The vent tubes 80 may optionally be secured at one or more corners 82 ofthe casing 62. In one non-limiting embodiment, vent tubes 80 are locatedwithin the corners 82 on the same side of the casing 62 (see FIG. 4B).In another non-limiting embodiment, vent tubes 80 are disposed withinopposite corners 82 of the casing 62 (see FIG. 4C). In yet anothernon-limiting embodiment, vent tubes 80 are positioned at each corner 82of the casing 62 (see FIG. 4D). In still another non-limitingembodiment, the vent tubes 80 are secured to the walls 66 of the casing62 at locations that are spaced from the corners 82 (see, for example,FIG. 4E).

The vent tubes 80 may embody any size or shape. In one non-limitingembodiment, the vent tubes 80 are configured as hollow cylinders forestablishing the flow pathways 85. In another non-limiting embodiment,the vent tubes 80 include a plurality of perforations 86 (see FIG. 4F)for ensuring free flow of the gaseous byproducts GB even if portions ofthe vent tubes 80 become blocked by solid electrode debris or otherdebris.

In another embodiment, shown in FIG. 5, the venting system 74 includes aspacer plate 88 for preventing blockage of the vent port 76. In onenon-limiting embodiment, the venting spacer plate 88 is mounted in a gap90 that extends between the vent port 76 and the electrode assembly 60.In another non-limiting embodiment, the spacer plate 88 is mounted to anunderside 92 of the top plate 64. The spacer plate 88, which may be madeof a metallic material, may be welded or otherwise secured to anyportion of the battery cell 56.

The spacer plate 88 is a rigid sub-structure mounted inside the batterycell 56 to ensure the reliable, unobstructed flow of gaseous byproductstoward the vent port 76. In one non-limiting embodiment, the spacerplate 88 is configured as an arched sheet of material. Other shapes arealso contemplated within the scope of this disclosure.

In yet another non-limiting embodiment, the spacer plate 88 includes aplurality of perforations 94 (see FIG. 6). The perforations 94 ensurethe free flow of gaseous byproducts even if portions of the spacer plate88 become blocked by solid electrode debris or other debris.

In yet another non-limiting embodiment, shown in FIG. 7, the ventingsystem 74 includes both vent tubes 80 and the spacer plate 88. The venttubes 80 may establish vertical flow pathways for directing gaseousbyproducts toward the vent port 76 (i.e., from the bottom toward the topof the battery cell 56), whereas the spacer plate 88 may preventblockage of the vent port 76 and establish lateral flow pathways forcommunicating the gaseous byproducts should the electrode assembly 60expand during a thermal runaway event.

Although the different non-limiting embodiments are illustrated ashaving specific components or steps, the embodiments of this disclosureare not limited to those particular combinations. It is possible to usesome of the components or features from any of the non-limitingembodiments in combination with features or components from any of theother non-limiting embodiments.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould be understood that although a particular component arrangement isdisclosed and illustrated in these exemplary embodiments, otherarrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A battery cell, comprising: a can assembly; anelectrode assembly housed inside said can assembly; and a venting systemincluding a vent port and at least one of a vent tube inside said canassembly or a spacer plate mounted between said vent port and saidelectrode assembly.
 2. The battery cell as recited in claim 1, whereinsaid can assembly includes a casing and a top plate.
 3. The battery cellas recited in claim 2, wherein said vent tube is attached to an interiorwall of said casing.
 4. The battery cell as recited in claim 2, whereinsaid vent tube is secured within a corner of said casing.
 5. The batterycell as recited in claim 2, wherein said vent tube includes a firstheight that is less than a second height of a wall of said casing. 6.The battery cell as recited in claim 2, wherein said vent port isdisposed in said top plate.
 7. The battery cell as recited in claim 1,wherein said vent tube establishes a flow pathway between differentportions of said can assembly.
 8. The battery cell as recited in claim1, comprising a plurality of vent tubes mounted inside said can assemblyand each establishing a flow pathway configured to communicate gaseousbyproducts toward said vent port.
 9. The battery cell as recited inclaim 1, wherein said spacer plate is mounted to an underside of a topplate of said can assembly.
 10. The battery cell as recited in claim 1,wherein said spacer plate is an arched sheet of material.
 11. Thebattery cell as recited in claim 1, wherein at least one of said venttube and said spacer plate includes a plurality of perforations.
 12. Thebattery cell as recited in claim 1, wherein said venting system includesboth of said vent tube and said spacer plate.
 13. A battery pack,comprising: a battery assembly that includes a plurality of batterycells, and each battery cell of said plurality of battery cells includesa venting system comprising: a vent tube configured to establish a firstflow pathway for communicating gaseous byproducts inside said batterycell; and a spacer plate configured to establish a second flow pathwayfor communicating said gaseous byproducts.
 14. The battery pack asrecited in claim 13, wherein said venting system includes a vent port.15. The battery pack as recited in claim 14, wherein said spacer plateis disposed between said vent port and an electrode assembly of saidbattery cell.
 16. The battery pack as recited in claim 13, wherein eachof said plurality of battery cells includes a can assembly including acasing and a top plate.
 17. The battery pack as recited in claim 16,wherein said vent tube is disposed in a corner of said casing.
 18. Thebattery pack as recited in claim 13, wherein said first flow pathway isa vertical flow pathway and said second flow pathway is a lateral flowpathway.
 19. The battery pack as recited in claim 13, wherein at leastone of said vent tube and said spacer plate includes a plurality ofperforations.
 20. The battery pack as recited in claim 13, wherein saidvent tube is a hollow cylinder and said spacer plate is an arched sheetof material.